The short answer is that I don't think you can in one go. You can 'subscribe' to specific topics, and that can be set to do so if you respond to a topic, but that's it for 'automatic' I believe. If we did have a feature like that and a lot of people used it, that could create an awful lot of overhead for the web server in busy periods. Let me suggest an alternative.
Bookmark this link (right click in Windows):http://www.cbxclub.com/forum/search.php?search_id=unreadposts
...and use that bookmark by default when you access the site. That will take you to what's new every time, although depending on your preferences for staying logged-in, it might require you to login each time too.
Will that come close enough to what you want Aris?